The subject matter disclosed herein relates to circuit breakers and, more particularly, to a contact system of a circuit breaker.
An electrical switching apparatus, such as a circuit breaker, provides protection for electrical systems from electrical fault conditions such as, for example, current overloads, short circuits, abnormal voltage and other fault conditions. Typically, circuit breakers include a housing and an operating mechanism which opens separable electrical contacts to interrupt the flow of current through the conductors of an electrical system in response to certain fault conditions.
To maintain a high withstand current rating, the contacts must be maintained in a closed condition at the current withstand rating. On the other hand, the short circuit let-through current must be capable of opening the contacts quickly during a short circuit condition. The drawback of having the contacts clamped or otherwise maintained in a tight closed condition is that the contacts may not be able to open quickly at the short circuit current level that the circuit breaker is rated for. Therefore, it is desirable to reliably disengage the contacts to the blow open condition of the circuit breaker in as rapid of a manner as possible, while ensuring that the contacts remain in the closed condition during normal operation of the circuit breaker.